Add extra library oslo.concurrency to oslo.config.generator.rc
Add extra library oslo.concurrency to oslo.config.generator.rc

We used extra library oslo.concurrency in Cinder, and oslo.concurrency
provides configuration options, we need include these options in sample
config file. This commit handles that.
Change-Id: I534539b7e87a3f5dc36722395cbe241a10b2d75e

cloudbase/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,j-griffith/cinder,Hybrid-Cloud/cinder,Akrog/cinder,j-griffith/cinder,eharney/cinder,Datera/cinder,nexusriot/cinder,openstack/cinder,eharney/cinder,potsmaster/cinder,openstack/cinder,duhzecca/cinder,petrutlucian94/cinder,tlakshman26/cinder-new-branch,Datera/cinder,julianwang/cinder,scality/cinder,saeki-masaki/cinder,leilihh/cinder,CloudServer/cinder,manojhirway/ExistingImagesOnNFS,nexusriot/cinder,JioCloud/cinder,potsmaster/cinder,scottdangelo/RemoveVolumeMangerLocks,CloudServer/cinder,julianwang/cinder,tlakshman26/cinder-https-changes,Nexenta/cinder,scality/cinder,takeshineshiro/cinder,winndows/cinder,ge0rgi/cinder,phenoxim/cinder,scottdangelo/RemoveVolumeMangerLocks,NetApp/cinder,phenoxim/cinder,tlakshman26/cinder-https-changes,dims/cinder,apporc/cinder,bswartz/cinder,tlakshman26/cinder-new-branch,rakeshmi/cinder,abusse/cinder,petrutlucian94/cinder,apporc/cinder,takeshineshiro/cinder,Paul-Ezell/cinder-1,mahak/cinder,manojhirway/ExistingImagesOnNFS,nikesh-mahalka/cinder,sasukeh/cinder,Paul-Ezell/cinder-1,rakeshmi/cinder,mahak/cinder,saeki-masaki/cinder,JioCloud/cinder,duhzecca/cinder,nikesh-mahalka/cinder,Akrog/cinder,Hybrid-Cloud/cinder,winndows/cinder,Nexenta/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,sasukeh/cinder,NetApp/cinder,abusse/cinder,cloudbase/cinder,dims/cinder,leilihh/cinder,bswartz/cinder